package com.wxg.netty.chat.server;

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.util.concurrent.GlobalEventExecutor;

/**
 * From : https://waylau.com/netty-chat/
 */
public class SimpleChatServerHandler extends SimpleChannelInboundHandler<String> {  // (1)
    // `SimpleChannelInboundHandler` 相当于是一个 Adaptor

    public static ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {  // (2)
        // 每当服务器收到新的客户端连接时，将客户端的Channel存入ChannelGroup列表中,
        // 并通知列表中的其他客户端Channel

        Channel incoming = ctx.channel();

        // Broadcast a message to multiple Channels
        channels.writeAndFlush("[SERVER] - " + incoming.remoteAddress() + " 加入\n");

        channels.add(ctx.channel());
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {  // (3)

        Channel incoming = ctx.channel();

        channels.writeAndFlush("[SERVER] - " + incoming.remoteAddress() + " 离开\n");

        // A closed Channel is automatically removed from ChannelGroup,
        // so there is no need to do `channels.remove(ctx.channel());`
    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String s) throws Exception {  // (4)
        Channel incoming = ctx.channel();
        for (Channel channel : channels){
            if(channel != incoming){
                channel.writeAndFlush("[" + incoming.remoteAddress() + "]" + s + "\n");
            }else{
                channel.writeAndFlush("[you]" + s + "\n");
            }
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {  // (5)
        Channel incoming = ctx.channel();
        System.out.println("SimpleChatClient:" + incoming.remoteAddress() + "在线");
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {  // (6)
        Channel incoming = ctx.channel();
        System.out.println("SimpleChatClient:" + incoming.remoteAddress() + "掉线");
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { // (7)
        Channel incoming = ctx.channel();
        System.out.println("SimpleChatClient:" + incoming.remoteAddress() + "异常");

        // 当出现异常时关闭连接
        cause.printStackTrace();
        ctx.close();
    }
}
